Multilayer ceramic electronic component

ABSTRACT

A multilayer ceramic electronic component includes a multilayer body including ceramic layers and internal conductive layers and a pair of external electrodes on both ends of the multilayer body in a length direction. The internal conductive layers include first internal conductive layers and second internal conductive layers. The pair of external electrodes include a first external electrode including a first base electrode layer connected to the first internal conductive layer, and a second external electrode including a second base electrode layer connected to the second internal conductive layer. The first and second base electrode layers each include a metal portion and non-metal portions in the metal portion. In a cross-sectional view perpendicular or substantially perpendicular to a width direction, an average area of non-metal portions in a first population of non-metal portions each with a circularity about 0.4 or less is about 12 μm 2  or less.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2022-066811 filed on Apr. 14, 2022. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a multilayer ceramic electroniccomponent.

2. Description of the Related Art

Conventionally, multilayer ceramic capacitors have been known asmultilayer ceramic electronic components. Generally, the multilayerceramic capacitors each include a multilayer body including dielectriclayers and internal electrode layers which are alternately laminatedtherein, and external electrodes provided on both end surfaces of themultilayer body. For example, Japanese Unexamined Patent ApplicationPublication No. 2003-243249 discloses a multilayer ceramic capacitorincluding the above-described structure, and also including externalelectrodes, each including a base electrode layer provided by firing.

SUMMARY OF THE INVENTION

Here, the base electrode layer of the external electrode has a role ofpreventing moisture from entering the end surface of the multilayer bodyfrom the outside in addition to a role of electrically connecting thebase electrode layer to the internal electrode layers. However, the baseelectrode layer often includes a non-metal portion such as a void, andin such a case, the non-metal portion becomes a moisture intrusion path,which may lower moisture resistance reliability.

Preferred embodiments of the present invention provide multilayerceramic electronic components, each having high moisture resistancereliability.

A multilayer ceramic electronic component according to a preferredembodiment of the present invention includes a multilayer body includinga plurality of ceramic layers and a plurality of internal conductivelayers which are alternately laminated therein in a laminationdirection, a first main surface and a second main surface which areopposed to each other in the lamination direction, a first end surfaceand a second end surface which are opposed to each other in a lengthdirection perpendicular or substantially perpendicular to the laminationdirection, and a first lateral surface and a second lateral surfacewhich are opposed to each other in a width direction perpendicular orsubstantially perpendicular to the lamination direction and the lengthdirection, and a pair of external electrodes provided on both ends ofthe multilayer body in the length direction and spaced apart from eachother, in which the plurality of internal conductive layers includefirst internal conductive layers each extending toward and exposed atthe first end surface, and second internal conductive layers eachextending toward and exposed at the second end surface, in which thepair of external electrodes include a first external electrode includinga first base electrode layer connected to the first internal conductivelayer, and a second external electrode including a second base electrodelayer connected to the second internal conductive layer, in which thefirst base electrode layer and the second base electrode layer eachinclude a metal portion and a plurality of non-metal portions in themetal portion, and in which, in a cross sectional view perpendicular orsubstantially perpendicular to the width direction, an average area of aplurality of non-metal portions in a first population of a plurality ofnon-metal portions each having a circularity of about 0.4 or less isabout 12 μm² or less.

According to preferred embodiments of the present invention, it ispossible to provide multilayer ceramic electronic components, eachhaving high moisture resistance reliability.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view of a multilayer ceramic capacitoraccording to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 .

FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2.

FIG. 4A is a cross-sectional view taken along the line IVA-IVA of FIG. 2. FIG. 4B is a cross-sectional view taken along the line IVB-IVB of FIG.2 .

FIG. 5 is an enlarged cross-sectional view based on an SEM photograph ofa portion indicated by R1 in FIG. 2 .

FIG. 6 is a diagram of an example of a non-metal portion having arelatively low circularity.

FIG. 7A is a diagram of a multilayer ceramic capacitor including atwo-portion structure. FIG. 7B is a diagram of a multilayer ceramiccapacitor including a three-portion structure. FIG. 7C is a diagram of amultilayer ceramic capacitor including a four-portion structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the drawings. Hereinafter, a multilayer ceramiccapacitor 1 defining and functioning as a multilayer ceramic electroniccomponent according to a preferred embodiment of the present inventionof the present invention will be described. FIG. 1 is an externalperspective view of a multilayer ceramic capacitor 1 according to apreferred embodiment. FIG. 2 is a cross-sectional view taken along theline II-II of FIG. 1 . FIG. 3 is a cross-sectional view taken along theline III-III of FIG. 2 . FIG. 4A is a cross-sectional view taken alongthe line IVA-IVA of FIG. 2 . FIG. 4B is a cross-sectional view takenalong the line IVB-IVB of FIG. 2 .

As shown in FIG. 1 , the multilayer ceramic capacitor 1 according to thepresent preferred embodiment has a rectangular or substantiallyrectangular parallelepiped shape. The multilayer ceramic capacitor 1includes a multilayer body 10 having a rectangular or substantiallyrectangular parallelepiped shape, and a pair of external electrodes 40provided at both end portions of the multilayer body 10 so as to bespaced apart from each other.

In FIG. 1 , an arrow T indicates a lamination (stacking) direction ofthe multilayer ceramic capacitor 1 and the multilayer body 10. Thelamination direction T is also referred to as a thickness direction anda height direction of the multilayer ceramic capacitor 1 and themultilayer body 10. In FIG. 1 , the arrow L indicates a length directionorthogonal or substantially orthogonal to the lamination direction T ofthe multilayer ceramic capacitor 1 and the multilayer body 10. In FIG. 1, the arrow W indicates a width direction orthogonal or substantiallyorthogonal to the lamination direction T and the length direction L ofthe multilayer ceramic capacitor 1 and the multilayer body 10. The pairof external electrodes 40 is provided at one end and the other end ofthe multilayer body 10 in the length direction L.

FIGS. 1 to 4B show XYZ orthogonal coordinate systems. The lengthdirection L of the multilayer ceramic capacitor 1 and the multilayerbody 10 corresponds to the X direction. The width direction W of themultilayer ceramic capacitor 1 and the multilayer body 10 corresponds tothe Y direction. The lamination direction T of the multilayer ceramiccapacitor 1 and the multilayer body 10 corresponds to the Z direction.Here, the cross section shown in FIG. 2 is also referred to as an LTcross section. The cross section shown in FIG. 3 is also referred to asa WT cross section. The cross section shown in FIGS. 4A and 4B is alsoreferred to as an LW cross section.

As shown in FIGS. 1 to 4B, the multilayer body 10 includes a first mainsurface TS1 and a second main surface TS2 which are opposed to eachother in the lamination direction T, a first end surface LS1 and asecond end surface LS2 which are opposed to each other in the lengthdirection L orthogonal or substantially orthogonal to the laminationdirection T, and a first lateral surface WS1 and a second lateralsurface WS2 which are opposed to each other in the width direction Worthogonal or substantially orthogonal to the lamination direction T andthe length direction L.

As shown in FIG. 1 , the multilayer body 10 has a rectangular orsubstantially rectangular parallelepiped shape. The dimension in thelength direction L of the multilayer body 10 may be longer than thedimension in the width direction W. The corner portions and ridgeportions of the multilayer body 10 are preferably rounded. The cornerportions are portions where the three surfaces of the multilayer bodyintersect, and the ridge portions are portions where the two surfaces ofthe multilayer body intersect. In addition, unevenness or the like maybe provided on a portion or the whole of the surface of the multilayerbody 10.

The dimensions of the multilayer body 10 are not particularly limited.However, when the dimension in the length direction L of the multilayerbody 10 is defined as L dimension, the L dimension is preferably about0.2 mm or more and about 6 mm or less, for example. When the dimensionof the multilayer body 10 in the lamination direction T is defined as Tdimension, the T dimension is preferably about 0.05 mm or more and about5 mm or less, for example. When the dimension of the multilayer body 10in the width direction W is defined as W dimension, the dimension W ispreferably about 0.1 mm or more and about 5 mm or less, for example.

As shown in FIGS. 2 and 3 , the multilayer body 10 includes an innerlayer portion 11, and a first main surface-side outer layer portion 12and a second main surface-side outer layer portion 13 that sandwich theinner layer portion 11 in the lamination direction T.

The inner layer portion 11 includes a plurality of dielectric layers 20functioning as a plurality of ceramic layers and a plurality of internalelectrode layers 30 functioning as a plurality of internal conductivelayers which are alternately laminated in the lamination direction T.The inner layer portion 11 includes, in the lamination direction T, fromthe internal electrode layer 30 located closest to the first mainsurface TS1 to the internal electrode layer 30 located closest to thesecond main surface TS2. In the inner layer portion 11, a plurality ofinternal electrode layers 30 are opposed to each other with thedielectric layer 20 interposed therebetween. The inner layer portion 11generates a capacitance and substantially defines and functions as acapacitor.

The plurality of dielectric layers 20 are each made of a dielectricmaterial. The dielectric material may be a dielectric ceramic includinga component such as BaTiO₃, CaTiO₃, SrTiO₃, or CaZrO₃. Furthermore, thedielectric material may be obtained by adding a secondary component suchas a Mn compound, an Fe compound, a Cr compound, a Co compound, or a Nicompound to the main component. The dielectric material particularlypreferably includes BaTiO₃ as a main component.

The thicknesses of the dielectric layers 20 are each preferably about0.2 μm or more and about 10 μm or less, for example. The number of thedielectric layers 20 to be laminated (stacked) is preferably fifteen ormore and 1200 or less, for example. The number of the dielectric layers20 refers to the total number of dielectric layers 20 in the inner layerportion 11, and dielectric layers 20 in the first main surface-sideouter layer portion 12 and the second main surface-side outer layerportion 13.

The plurality of internal electrode layers 30 includes a plurality offirst internal electrode layers 31 functioning as a plurality of firstinternal conductive layers and a plurality of second internal electrodelayers 32 functioning as a plurality of second internal conductivelayers. The first internal electrode layers 31 and the second internalelectrode layers 32 are alternately provided in the lamination directionT with the dielectric layers 20 interposed therebetween. The firstinternal electrode layers 31 each extend toward the first end surfaceLS1 and are each exposed at the first end surface LS1. The secondinternal electrode layers 32 each extend toward the second end surfaceLS2 and are each exposed at the second end surface LS2. In the followingdescription, when it is not necessary to distinguish between the firstinternal electrode layer 31 and the second internal electrode layer 32,the first internal electrode layer 31 and the second internal electrodelayer 32 may be collectively referred to as an internal electrode layer30.

As shown in FIG. 4A, the first internal electrode layers 31 each includea first counter portion 31A and a first extension portion 31B. The firstcounter portion 31A is a region opposed to the second internal electrodelayer 32 with the dielectric layer 20 interposed therebetween, and islocated inside the multilayer body 10. The first extension portion 31Bis a portion which extends from the first counter portion 31A toward thefirst end surface LS1, and is exposed at the first end surface LS1.

As shown in FIG. 4B, the second internal electrode layer 32 includes asecond counter portion 32A and a second extension portion 32B. Thesecond counter portion 32A is a region opposed to the first internalelectrode layer 31 with the dielectric layer 20 interposed therebetween,and is located inside the multilayer body 10. The second extensionportion 32B is a portion extending from the second counter portion 32Atoward the second end surface LS2, and is exposed at the second endsurface LS2.

In the present preferred embodiment, the first counter portion 31A andthe second counter portion 32A are opposed to each other with thedielectric layer 20 interposed therebetween, such that a capacitance isgenerated, and the characteristics of a capacitor are developed.

The shapes of the first counter portion 31A and the second counterportion 32A are not particularly limited, but are preferably rectangularor substantially rectangular. However, the corner portions of therectangular shape may be rounded, or the corner portions of therectangular or substantially rectangular shape may be providedobliquely. The shapes of the first extension portion 31B and the secondextension portion 32B are not particularly limited, but are preferablyrectangular or substantially rectangular. However, the corner portionsof the rectangular shape may be rounded, or the corner portions of therectangular shape may be provided obliquely.

The dimension of the first counter portion 31A in the width direction Wand the dimension of the first extension portion 31B in the widthdirection W may be the same, or either one of them may be smaller. Thedimension of the second counter portion 32A in the width direction W andthe dimension of the second extension portion 32B in the width directionW may be the same, or either one of them may be narrower.

The first internal electrode layers 31 and the second internal electrodelayers 32 are each made of an appropriate electrically conductivematerial including a metal such as Ni, Cu, Ag, Pd or Au, or an alloyincluding at least one of these metals. When using an alloy, the firstinternal electrode layers 31 and the second internal electrode layers 32may be each made of, for example, an Ag—Pd alloy.

The thicknesses of the first internal electrode layers 31 and the secondinternal electrode layers 32 are each preferably, for example, about 0.2μm or more and about 2.0 μm or less. The total number of the firstinternal electrode layers 31 and the second internal electrode layers 32is preferably fifteen or more and 1000 or less.

As shown in FIGS. 2 and 3 , the first main surface side-outer layerportion 12 is located adjacent to the first main surface TS1 of themultilayer body 10. The first main surface side-outer layer portion 12includes a plurality of dielectric layers 20 located between the firstmain surface TS1 and the internal electrode layer 30 closest to thefirst main surface TS1. On the other hand, the second main surfaceside-outer layer portion 13 is located adjacent to the second mainsurface TS2 of the multilayer body 10. The second main surfaceside-outer layer portion 13 includes a plurality of dielectric layers 20located between the second main surface TS2 and the internal electrodelayer 30 closest to the second main surface TS2. The dielectric layers20 used in the first main surface side-outer layer portion 12 and thesecond main surface side-outer layer portion 13 may be the same as thedielectric layers 20 used in the inner layer portion 11.

The multilayer body 10 includes a counter electrode portion 11E. Thecounter electrode portion 11E is a portion where the first counterportion 31A of the first internal electrode layer 31 and the secondcounter portion 32A of the second internal electrode layer 32 areopposed to each other. The counter electrode portion 11E defines andfunctions as a portion of the inner layer portion 11. FIGS. 4A and 4Beach show the range of the counter electrode portion 11E in the widthdirection W and the length direction L. The counter electrode portion11E is also referred to as a capacitor active portion.

The multilayer body 10 includes lateral surface side-outer layerportions. The lateral surface side-outer layer portions include a firstlateral surface side-outer layer portion WG1 and a second lateralsurface side-outer layer portion WG2. The first lateral surfaceside-outer layer portion WG1 is a portion including the dielectric layer20 located between the counter electrode portion 11E and the firstlateral surface WS1. The second lateral surface side-outer layer portionWG2 is a portion including the dielectric layer 20 located between thecounter electrode portion 11E and the second lateral surface WS2. FIGS.3, 4A and 4B each show the ranges of the first lateral surfaceside-outer layer portion WG1 and the second lateral surface side-outerlayer portion WG2 in the width direction W. The lateral surfaceside-outer layer portion is also referred to as a W gap or a side gap.

The multilayer body 10 includes end surface side-outer layer portions.The end surface side-outer layer portions include a first end surfaceside-outer layer portion LG1 and a second end surface side-outer layerportion LG2. The first end surface side-outer layer portion LG1 is aportion including the dielectric layer 20 and the first extensionportion 31B located between the counter electrode portion 11E and thefirst end surface LS1. That is, the first end surface side-outer layerportion LG1 includes the portions of the plurality of dielectric layers20 adjacent to the first end surface LS1 and the plurality of firstextension portions 31B. The second end surface side-outer layer portionLG2 is a portion including the dielectric layer 20 and the secondextension portion 32B located between the counter electrode portion 11Eand the second end surface LS2. That is, the second end surfaceside-outer layer portion LG2 includes the portions of the plurality ofdielectric layers 20 adjacent to the second end surface LS2 and theplurality of second extension portions 32B. FIGS. 2, 4A, and 4B eachshow the ranges of the first end surface side-outer layer portion LG1and the second end surface side-outer layer portion LG2 in the lengthdirection L. The end surface side-outer layer portion is also referredto as an L gap or an end gap.

As shown in FIGS. 1 and 2 , the external electrodes 40 include a firstexternal electrode 40A adjacent to the first end surface LS1 of themultilayer body 10 and a second external electrode 40B adjacent to thesecond end surface LS2 of the multilayer body 10.

It is to be noted that the basic configurations of the first externalelectrode 40A and the second external electrode 40B are the same.Furthermore, the first external electrode 40A and the second externalelectrode 40B have a shape that is substantially plane symmetrical withrespect to the WT cross section at the center in the length direction Lof the multilayer ceramic capacitor 1. Therefore, in the followingdescription, when it is not necessary to distinguish between the firstexternal electrode 40A and the second external electrode 40B, the firstexternal electrode 40A and the second external electrode 40B may becollectively referred to as an external electrode 40.

The first external electrode 40A is provided on the first end surfaceLS1. The first external electrode 40A is in contact with the firstextension portion 31B of each of the plurality of first internalelectrode layers 31 exposed at the first end surface LS1. With such aconfiguration, the first external electrode 40A is electricallyconnected to the plurality of first internal electrode layers 31. Thefirst external electrode 40A may be provided on a portion of the firstmain surface TS1 and a portion of the second main surface TS2, and alsoon a portion of the first lateral surface WS1 and a portion of thesecond lateral surface WS2. In the present preferred embodiment, thefirst external electrode 40A extends from the first end surface LS1 to aportion of the first main surface TS1 and to a portion of the secondmain surface TS2, and to a portion of the first lateral surface WS1 andto a portion of the second lateral surface WS2.

The second external electrode 40B is provided on the second end surfaceLS2. The second external electrode 40B is in contact with the secondextension portion 32B of each of the plurality of second internalelectrode layers 32 exposed at the second end surface LS2. With such aconfiguration, the second external electrode 40B is electricallyconnected to the plurality of second internal electrode layers 32. Thesecond external electrodes 40B may be provided on a portion of the firstmain surface TS1 and a portion of the second main surface TS2, and alsoon a portion of the first lateral surface WS1 and a portion of thesecond lateral surface WS2. In the present preferred embodiment, thesecond external electrode 40B extends from the second end surface LS2 toa portion of the first main surface TS1 and to a portion of the secondmain surface TS2, and to a portion of the first lateral surface WS1 anda portion of the second lateral surface WS2.

As described above, in the multilayer body 10, the capacitance isgenerated by the first counter portions 31A of the first internalelectrode layers 31 and the second counter portions 32A of the secondinternal electrode layers 32 which are opposed to each other with thedielectric layers 20 interposed therebetween. Therefore, characteristicsof the capacitor are provided between the first external electrode 40Ato which the first internal electrode layers 31 are connected and thesecond external electrode 40B to which the second internal electrodelayers 32 are connected.

As shown in FIGS. 2, 4A, and 4B, the first external electrode 40Aincludes a first base electrode layer 50A and a first plated layer 60Aprovided on the first base electrode layer 50A. Furthermore, the secondexternal electrode 40B includes a second base electrode layer 50B and asecond plated layer 60B provided on the second base electrode layer 50B.

The first base electrode layer 50A is provided on the first end surfaceLS1. The first base electrode layer 50A is connected to the firstextension portion 31B of each of the plurality of first internalelectrode layers 31 exposed at the first end surface LS1. In the presentpreferred embodiment, the first base electrode layer 50A extends fromthe first end surface LS1 to a portion of the first main surface TS1 andto a portion of the second main surface TS2, and to a portion of thefirst lateral surface WS1 and to a portion of the second lateral surfaceWS2.

The second base electrode layer 50B is provided on the second endsurface LS2. The second base electrode layer 50B is in contact with thesecond extension portion 32B of each of the plurality of second internalelectrode layers 32 exposed at the second end surface LS2. In thepresent preferred embodiment, the second base electrode layer 50Bextends from the second end surface LS2 to a portion of the first mainsurface TS1 and to a portion of the second main surface TS2, and to aportion of the first lateral surface WS1 and to a portion of the secondlateral surface WS2.

The first base electrode layer 50A and the second base electrode layer50B of the present preferred embodiment are fired layers. It ispreferable that the fired layers each include both a metal component,and either a glass component or a ceramic component, or both the glasscomponent and the ceramic component. The metal component includes, forexample, at least one selected from Cu, Ni, Ag, Pd, Ag—Pd alloys, Au,and the like. The glass component includes, for example, at least oneselected from B, Si, Ba, Mg, Al, Li, and the like. As the ceramiccomponent, the same or substantially same ceramic material as that ofthe dielectric layer 20 may be used, or a different ceramic material maybe used. Ceramic components include, for example, at least one selectedfrom BaTiO₃, CaTiO₃, (Ba, Ca)TiO₃, SrTiO₃, CaZrO₃, and the like.

The fired layer is obtained by, for example, applying an electricallyconductive paste including glass and metal to the multilayer body 10 andfiring it. The fired layer can be obtained by simultaneously firing(cofiring) a multilayer chip before firing, which is a material of themultilayer body 10 having a plurality of internal electrodes anddielectric layers, and an electrically conductive paste applied to themultilayer chip. Alternatively, the multilayer chip may be fired toobtain the multilayer body 10, following which an electricallyconductive paste may be applied to the multilayer body 10 and theresulting product may be fired. In a case of the above-describedcofiring, it is preferable that the fired layer is formed by baking aceramic material added instead of the glass component. In such a case,it is particularly preferable to use, as the ceramic material to beadded, the same or substantially the same kind of ceramic material asthe dielectric layer 20. The fired layer may include a plurality oflayers.

The thickness of the first base electrode layer 50A located on the firstend surface LS1 in the length direction L is preferably, for example,about 10 μm or more and about 200 μm or less at the center of the firstbase electrode layer 50A in the lamination direction T and the widthdirection W.

The thickness of the second base electrode layer 50B located on thesecond end surface LS2 in the length direction L is preferably, forexample, about 10 μm or more and about 200 μm or less at the center ofthe second base electrode layer 50B in the lamination direction T andthe width direction W.

When providing the first base electrode layer 50A to at least one ofportions of the first main surface TS1 and the second main surface TS2,the thickness in the lamination direction T of the first base electrodelayer 50A provided at this portion is preferably about 3 μm or more andabout 40 μm or less at the center in the length direction L and thewidth direction W of the first base electrode layer 50A provided at thisportion, for example.

When providing the first base electrode layer 50A to portions of atleast one of the first lateral surface WS1 and the second lateralsurface WS2, the thickness in the width direction W of the first baseelectrode layer 50A provided at this portion is preferably about 3 μm ormore and about 40 μm or less at the center in the length direction L andthe height direction T of the first base electrode layer 50A provided atthis portion, for example.

When providing the second base electrode layer 50B to portions of atleast one of the first main surface TS1 and the second main surface TS2,the thickness in the lamination direction T of the second base electrodelayer 50B provided at this portion is preferably about 3 μm or more andabout 40 μm or less at the center in the length direction L and thewidth direction W of the second base electrode layer 50B provided atthis portion, for example.

When providing the second base electrode layer 50B to portions of atleast one of the first lateral surface WS1 and the second lateralsurface WS2, the thickness in the width direction W of the second baseelectrode layer 50B provided at this portion is preferably about 3 μm ormore and about 40 μm or less at the center in the length direction L andthe height direction T of the second base electrode layer 50B providedat this portion, for example.

The first plated layer 60A covers the first base electrode layer 50A.

The second plated layer 60B covers the second base electrode layer 50B.

The first plated layer 60A and the second plated layer 60B may eachinclude at least one selected from Cu, Ni, Sn, Ag, Pd, a Ag—Pd alloy,Au, and the like. The first plated layer 60A and the second plated layer60B may each include a plurality of layers. The first plated layer 60Aand the second plated layer 60B each preferably include a two-layerstructure including a Sn plated layer on a Ni plated layer.

The first plated layer 60A covers the first base electrode layer 50A. Inthe present preferred embodiment, the first plated layer 60A includes afirst Ni plated layer 61A, and a first Sn plated layer 62A provided onthe first Ni plated layer 61A.

The second plated layer 60B covers the second base electrode layer 50B.In the present preferred embodiment, the second plated layer 60Bincludes a second Ni plated layer 61B, and a second Sn plated layer 62Bprovided on the second Ni plated layer 61B.

The Ni plated layer prevents the first base electrode layer 50A and thesecond base electrode layer 50B from being eroded by solder whenmounting the multilayer ceramic capacitor 1. Furthermore, the Sn platedlayer improves the wettability of the solder when mounting themultilayer ceramic capacitor 1. This facilitates the mounting of themultilayer ceramic capacitor 1. The thickness of each of the first Niplated layer 61A, the first Sn plated layer 62A, the second Ni platedlayer 61B, and the second Sn plated layer 62B is preferably about 2 μmor more and about 10 μm or less, for example.

The external electrode 40 of the present preferred embodiment mayinclude an electrically conductive resin layer including electricallyconductive particles and a thermosetting resin, for example. Theelectrically conductive resin layer may cover the fired layer. When theelectrically conductive resin layer covers the fired layer, theelectrically conductive resin layer is provided between the fired layerand the plated layers (the first plated layer 60A and the second platedlayer 60B). The electrically conductive resin layer may completely coverthe fired layer or may partially cover the fired layer.

The electrically conductive resin layer including a thermosetting resinis more flexible than an electrically conductive layer made of, forexample, a plated film or a fired product of an electrically conductivepaste. Therefore, even when an impact caused by physical shock orthermal cycle is applied to the multilayer ceramic capacitor 1, theelectrically conductive resin layer defines and functions as a bufferlayer. Therefore, the electrically conductive resin layer reduces orprevents the occurrence of cracking in the multilayer ceramic capacitor1.

Metals of the electrically conductive particles may be, for example, Ag,Cu, Ni, Sn, Bi or alloys including them. The electrically conductiveparticle preferably includes Ag, for example. The electricallyconductive particle is a metal powder of Ag, for example. Ag is suitableas an electrode material because of its lowest resistivity among metals.In addition, since Ag is a noble metal, it is not likely to be oxidized,and weatherability thereof is high. Therefore, the metal powder of Ag issuitable as the electrically conductive particle.

Furthermore, the electrically conductive particle may be a metal powdercoated on the surface of the metal powder with Ag. When using thosecoated with Ag on the surface of the metal powder, the metal powder ispreferably Cu, Ni, Sn, Bi, or an alloy powder thereof. In order to makethe metal of the base material inexpensive while keeping thecharacteristics of Ag, it is preferable to use a metal powder coatedwith Ag.

Furthermore, the electrically conductive particle may be formed bysubjecting Cu and Ni to an oxidation prevention treatment. Furthermore,the electrically conductive particle may be a metal powder coated withSn, Ni, and Cu on the surface of the metal powder. When using thosecoated with Sn, Ni, and Cu on the surface of the metal powder, the metalpowder is preferably Ag, Cu, Ni, Sn, Bi, or an alloy powder thereof.

The shape of the electrically conductive particle is not particularlylimited. For the electrically conductive particle, a spherical metalpowder, a flat metal powder, or the like can be used. However, it ispreferable to use a mixture of a spherical metal powder and a flat metalpowder.

The electrically conductive particles included in the electricallyconductive resin layer mainly play a role of ensuring the conductivityof the electrically conductive resin layer. Specifically, by a pluralityof electrically conductive particles being in contact with each other,an energization path is provided inside the electrically conductiveresin layer.

The resin of the electrically conductive resin layer may include, forexample, at least one selected from a variety of known thermosettingresins such as epoxy resin, phenolic resin, urethane resin, siliconeresin, polyimide resin, and the like. Among those, epoxy resin isexcellent in heat resistance, moisture resistance, adhesion, etc., andthus is one of the most preferable resins. Furthermore, it is preferablethat the resin of the electrically conductive resin layer include acuring agent together with a thermosetting resin. When epoxy resin isused as a base resin, the curing agent for the epoxy resin may bevarious known compounds such as phenols, amines, acid anhydrides,imidazoles, active esters, and amide-imides.

The electrically conductive resin layer may include a plurality oflayers. The thickest portion of the electrically conductive resin layeris preferably about 10 μm or more and about 150 μm or less, for example.

The basic configuration of the multilayer ceramic capacitor 1 accordingto the preferred embodiment is described as above. When the dimension inthe length direction of the multilayer ceramic capacitor 1 including themultilayer body 10 and the external electrodes 40 is defined as the Ldimension, the L dimension is preferably about 0.2 mm or more and about6 mm or less, for example. Furthermore, when the dimension in thelamination direction of the multilayer ceramic capacitor 1 is defined asthe T dimension, the T dimension is preferably about 0.05 mm or more andabout 5 mm or less, for example. Furthermore, when the dimension in thewidth direction of the multilayer ceramic capacitor 1 is defined as theW dimension, the W dimension is preferably about 0.1 mm or more andabout 5 mm or less, for example.

The inventors of preferred embodiments of the present inventionthoroughly conducted investigations, experiments, and simulations, andhave discovered that it is desirable to set the base electrode layer indirect contact with the multilayer body, i.e., the non-metal portionincluded in the first base electrode layer 50A and the second baseelectrode layer 50B of the present preferred embodiment in anappropriate state in order to improve the moisture-resistancereliability of the multilayer ceramic capacitors. This point will bedescribed below.

FIG. 5 is an enlarged cross-sectional view based on an SEM (scanningelectron microscope) photograph of a portion indicated by R1 in FIG. 2 .FIG. 5 is a portion of an LT cross section perpendicular orsubstantially perpendicular to the width direction W of the multilayerbody 10 in the multilayer ceramic capacitor 1. FIG. 5 shows the firstbase electrode layer 50A, a portion of the first Ni plated layer 61A,and a portion of the multilayer body 10. FIG. 5 shows the dielectriclayer 20 and the plurality of first internal electrode layers 31 in themultilayer body 10. The first base electrode layer 50A is in contactwith the first internal electrode layer 31 exposed at the first endsurface LS1 of the multilayer body 10.

The second base electrode layer 50B of the present preferred embodimentalso includes a cross-sectional structure similar to that of FIG. 5 .Therefore, the structure of the first base electrode layer 50A, whichwill be described with reference to FIG. 5 , is the structure of thesecond base electrode layer 50B. In the following description, when itis not necessary to distinguish between the first base electrode layer50A and the second base electrode layer 50B, the first base electrodelayer 50A and the second base electrode layer 50B may be collectivelyreferred to as a base electrode layer 50.

As shown in FIG. 5 , the base electrode layer 50 includes a metalportion 70 and a plurality of non-metal portions 80 existing in themetal portion 70.

The metal portion 70 includes at least one metal component selected fromCu, Ni, Ag, Pd, an Ag—Pd alloy, Au, and the like included in the firedlayer of the base electrode layer 50. The plurality of non-metalportions 80 are dispersed in the metal portion 70.

Although the plurality of non-metal portions 80 are mainly voids, allthe plurality of non-metal portions 80 may not be voids, and some of theplurality of non-metal portions 80 may include or partially include aglass component including Ba or Si. Furthermore, all the non-metalportion 80 may be made of a glass component including Ba or Si. Theplurality of non-metal portions 80 have different circularities andaverage areas.

In the base electrode layer 50 of the present preferred embodiment, theaverage area of the plurality of non-metal portions 80 in the firstpopulation including the non-metal portions 80 having a circularity ofabout 0.4 or less is preferably about 12 μm² or less in the LTcross-sectional view perpendicular or substantially perpendicular to thewidth direction W as shown in FIG. 5 , for example.

Furthermore, in the base electrode layer 50 of the present preferredembodiment, the proportion of the non-metal portions 80 is preferablyabout 17.2% or less in the LT cross-sectional view perpendicular orsubstantially perpendicular to the width direction W as shown in FIG. 5, for example.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, non-metal portions 80 each having a low circularity amongthe non-metal portions 80 existing in the base electrode layer 50 haverelatively small areas. In the multilayer ceramic capacitor includingthe base electrode layer, the base electrode layer typically includesnon-metal portions such as the non-metal portions 80 of the presentpreferred embodiment.

The non-metal portions 80 each define and function as a path throughwhich moisture enters the inside from the outside. This may lower themoisture resistance reliability of the multilayer ceramic capacitor 1.In particular, when the proportion of the non-metal portions 80 existingin the base electrode layer 50 increases, moisture resistancereliability tends to decrease. In addition, even when the proportion ofthe non-metal portions 80 is not so high, for example, when thenon-metal portion 80 has a long and thin shape, there is a possibilitythat a structure in which moisture is likely to penetrate may be formeddepending on the direction in the length direction of the non-metalportion 80 or the degree of connection of the plurality of non-metalportions 80. In order to improve the moisture resistance reliability ofthe multilayer ceramic capacitor 1, it is conceivable to increase thethickness of the base electrode layer 50. However, in such a case, thechip size of the multilayer ceramic capacitor 1 becomes large, thuspreventing the reduction in size of the components. When the size of themultilayer ceramic capacitor 1 is not changed, the thickness of the baseelectrode layer 50 is increased to reduce the size of the multilayerbody 10, resulting in a decrease in the capacitance of the capacitor.

FIG. 6 shows an example of the non-metal portion 80 having a relativelylow circularity. The non-metal portion 80 has a circularity of about0.25, for example. When there are a plurality of non-metal portions 80having a low circularity and the plurality of non-metal portions 80 arelarge in size, moisture may easily enter the non-metal portions 80.

In the present preferred embodiment, in the LT cross-sectional view ofthe base electrode layer 50, when the population of non-metal portions80 each having a circularity of about 0.4 or less is taken as a firstpopulation, the average area of the plurality of non-metal portions 80of the first population is about 12 μm² or less, and specifically, inthe region shown in FIG. 5 , the average area is about 6.3 μm², forexample. With such a configuration, even when the non-metal portions 80are included in the base electrode layer 50, the non-metal portions 80each having a low degree of circularity, which facilitates thepenetration of moisture, are small in size, such that the non-metalportions 80 are each less likely to define and function as a paththrough which moisture penetrates. Therefore, it is possible to improvemoisture resistance reliability.

In the present preferred embodiment, the average area of the pluralityof non-metal portions 80 of the first population is preferably about 2μm² or more and about 12 μm² or less, and more preferably about 2 μm² ormore and about 9 μm² or less, for example. This further improvesmoisture resistance reliability.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the proportion of the non-metal portions 80 existing in thebase electrode layer 50 in the LT cross-sectional view may be, forexample, about 1% or more and about 30% or less, and is preferably about17.2% or less. More specifically, the proportion of the non-metalportions 80 existing in the base electrode layer 50 is preferably about1.5% or more and about 17.2% or less, and more preferably about 5% ormore and about 15% or less, for example. Even when the non-metal portion80 is included in the base electrode layer 50 and the proportion of thenon-metal portions 80 existing in the base electrode layer 50 fallswithin such a range, it is possible to achieve the advantageous effectof the present preferred embodiment, that is, the advantageous effect ofimproving moisture resistance reliability.

Next, a method of measuring various parameters such as the circularityof the non-metal portion 80, the average area of the non-metal portions80, and the proportion of the non-metal portions 80 existing in the baseelectrode layer 50 in the present preferred embodiment will bedescribed.

First, the multilayer ceramic capacitor 1 is polished from the firstlateral surface WS1 or the second lateral surface WS2 to a positionlocated at about ½ of the width direction W. Thereby, the LT crosssection at the middle position in the width direction W of themultilayer ceramic capacitor 1 is exposed. Next, the LT cross sectionexposed by polishing is observed by SEM. Specifically, a portionincluding the base electrode layer 50 in the LT cross section is imagedas a reflected electron image. In the reflected electron image, thedifference in resistance value is reflected as contrast, the metalportion 70 appears relatively white, and the non-metal portion 80appears darker than the metal portion 70. It is to be noted that theimaging magnification is set to 2000 times, and a portion of the baseelectrode layer 50 in the reflected electron image is set as an analysistarget range.

A total of four reflected electron images of two locations of the firstbase electrode layer 50A and two locations of the second base electrodelayer 50B are obtained. In FIG. 2 , four positions of the reflectedelectron image acquisition are indicated by R1, R2, R3, and R4. R1refers to a portion closest to the first main surface TS1 of the firstbase electrode layer 50A in contact with the inner layer portion 11 ofthe multilayer body 10. R2 refers to a portion closest to the secondmain surface TS2, of the first base electrode layer 50A in contact withthe inner layer portion 11 of the multilayer body 10. R3 refers to aportion closest to the first main surface TS1, of the second baseelectrode layer 50B in contact with the inner layer portion 11 of themultilayer body 10. R4 refers to a portion closest to the second mainsurface TS2, of the second base electrode layer 50B in contact with theinner layer portion 11 of the multilayer body 10. All of the lengths ofR1, R2, R3, and R4 in the lamination direction T are about 80 μm, forexample.

In the base electrode layer 50, the four regions corresponding to therespective reflected electron image acquisition positions R1, R2, R3,and R4 are likely to have a small thickness, which is a dimensioncorresponding to the length direction L, and have a high degree ofinfluence on moisture resistance reliability. Therefore, the state ofthe base electrode layer 50 in these portions is important from theviewpoint of moisture resistance reliability.

The acquired reflected electron image is binarized by the image analysissoftware “WinROOF” (available from Mitani Corporation) to identify themetal portion 70 and a plurality of non-metal portions 80 existing inthe metal portion 70. Using the binarized image, various parameters suchas the area of each non-metal portion 80 existing in the base electrodelayer 50 are calculated. Furthermore, the proportion of the non-metalportions 80 existing in the base electrode layer 50 is calculated.

The area of the non-metal portion 80 is calculated based on thebinarized image obtained by binarizing the reflected electron image.When the area of the non-metal portion 80 is less than about 2.0 μm², itmay be noise instead of the non-metal portion 80. Therefore, in order toexclude the influence of noise, the non-metal portions 80 of less thanabout 2.0 μm² are excluded from the analysis target.

For each non-metal portion 80, the circularity of the non-metal portion80 is calculated by the following equation (1) based on the area of thenon-metal portion 80 and the circumference (the length of the outline)of the non-metal portion 80.

Circularity=4π×(area)/(circumferential length)²   (1)

A set of non-metal portions 80 having a circularity of about 0.4 or lessamong all the non-metal portions 80 (excluding those having an area ofless than about 2.0 μm² as described above) identified in the analysistarget range of the reflected electron images acquired at the fourlocations of the reflected electron image acquisition positions R1, R2,R3, and R4 is set as the first population. The average area of thenon-metal portions 80 in the first population is calculated based on thearea of each non-metal portion 80 of the first population.

Based on the area of the analysis target range and the area of thenon-metal portion 80, the proportion of the non-metal portion 80existing in the base electrode layer 50 is calculated by the followingequation (2).

Proportion (%) of the non-metal portion=(area of the non-metalportion/area of the analysis target range)×100   (2)

For each of the four analysis target ranges (R1, R2, R3, and R4), theproportion of the non-metal portions 80 is calculated. Then, the averagevalue is calculated as the proportion of the non-metal portion 80 of thepresent preferred embodiment.

As described above, the measurement target range for calculating theaverage area of the non-metal portions 80 existing in the firstpopulation of the non-metal portions 80 having a circularity of about0.4 or less is a set of the analysis target ranges at the four locations(R1, R2, R3, and R4) described above. Specifically, the measurementtarget ranges are portions adjacent to the first main surface TS1 andportions adjacent to the second main surface TS2 of the first baseelectrode layer 50A and the second base electrode layer 50B, which arein contact with the inner layer portion 11 of the multilayer body 10.More specifically, the measurement target ranges are a portion, in thefirst base electrode layer 50A and the second base electrode layer 50B,from the position of the boundary portion in the lamination directionbetween the inner layer portion 11 and the first outer layer portion 12of the multilayer body 10 to the position of 80 pm toward the center inthe lamination direction of the multilayer body 10, and a portion, inthe first base electrode layer 50A and the second base electrode layer50B, from the position of the boundary portion in the laminationdirection between the inner layer portion 11 and the second outer layerportion 13 of the multilayer body 10 to the position of about 80 pmtoward the center in the lamination direction of the multilayer body 10.

Next, a non-limiting example of a method of manufacturing the multilayerceramic capacitor 1 of the present preferred embodiment will bedescribed. The method of manufacturing the multilayer ceramic capacitor1 of the present preferred embodiment is not limited as long as itsatisfies the above-mentioned requirements. However, a preferredmanufacturing method includes the following steps, for example. Thedetails of each step will be described below.

A dielectric sheet for manufacturing the dielectric layer 20 and anelectrically conductive paste for manufacturing the internal electrodelayer 30 are prepared. Both the dielectric sheet for the dielectriclayer 20 and the electrically conductive paste for the internalelectrode layer 30 include a binder and a solvent. The binders andsolvents may be known. The paste made of an electrically conductivematerial is, for example, a paste obtained by adding an organic binderand an organic solvent to metal powder.

An electrically conductive paste for manufacturing the internalelectrode layer 30 is printed on the dielectric sheet by using aprinting plate designed to have the shape of the internal electrodelayer 30 of the present preferred embodiment, for example, by screenprinting or gravure printing. With such a configuration, a dielectricsheet having a pattern of the first internal electrode layer 31 providedthereon and a dielectric sheet having a pattern of the second internalelectrode layer 32 provided thereon are prepared.

By laminating a predetermined number of dielectric sheets on whichpatterns of the internal electrode layers 30 are not printed, a portiondefining and functioning as the first main surface side-outer layerportion 12 adjacent to the first main surface TS1 is formed. On top ofthat, the dielectric sheets on which the pattern of the first internalelectrode layer 31 is printed and the dielectric sheets on which thepattern of the second internal electrode layer 32 is printed aresequentially and alternately laminated to form a portion defining andfunctioning as the inner layer portion 11. A predetermined number ofdielectric sheets on which patterns of the internal electrode layers 30are not printed are laminated on the portion defining and functioning asthe inner layer portion 11 to form a portion defining and functioning asthe second main surface side-outer layer portion 13 adjacent to thesecond main surface TS2. Thus, a multilayer sheet is obtained.

Next, the multilayer sheet is pressed in the laminating direction byhydrostatic pressing or other methods to prepare a multilayer block.

Next, the multilayer block is cut to a predetermined size and dividedinto individual pieces to obtain a plurality of multilayer chips.Thereafter, the multilayer chips may be polished by barrel polishing orthe like to round the corner portions and the ridge portions.

Next, the multilayer chips are fired to obtain the multilayer body 10.The firing temperature at this time depends on the materials of thedielectric layer 20 and the internal electrode layer 30, but ispreferably about 900° C. or higher and about 1400° C. or lower, forexample.

The electrically conductive paste defining and functioning as the baseelectrode layer 50 is applied to both end surfaces of the multilayerbody 10. In the present preferred embodiment, the base electrode layer50 is a fired layer. The fired layer can be formed by applying anelectrically conductive paste including a glass component and a metal tothe multilayer body 10 by a method such as dipping, and then performingfiring treatment. The temperature of the firing treatment at this timeis preferably about 700° C. or higher and about 900° C. or lower.

Furthermore, the multilayer chips before firing and the electricallyconductive paste applied to the multilayer chip may be firedsimultaneously. In such a case, the fired layer is preferably formed byfiring a ceramic material added instead of the glass component. At thistime, it is particularly preferable to use, as the ceramic material tobe added, the same kind of ceramic material as the dielectric layer 20.In this case, an electrically conductive paste is applied to themultilayer chip before firing, and the multilayer chip and theelectrically conductive paste applied to the multilayer chip are firedat the same time to form the multilayer body 10 in which the fired layeris formed.

By changing the shape and particle size distribution of the copperpowder added to the electrically conductive paste, it is possible tocontrol the circularity of the non-metal portions 80 existing in thebase electrode layer 50. The circularity of the non-metal portions 80improves with using the spherical powder as the copper powder andsharper particle size distribution of the copper powder. Conversely, thecircularity of the non-metal portion 80 decreases with using flat powderas the copper powder and a broader particle size distribution of thecopper powder.

It is possible to control the average area of the non-metal portions 80existing in the base electrode layer 50 by changing the particlediameter and firing temperature of the copper powder and the glasscomponent. As the particle diameters of the copper powder and the glasscomponent are smaller and the firing temperature is higher, the averagearea of the non-metal portion 80 becomes smaller. Conversely, as theparticle diameters of the copper powder and the glass component arelarger and the firing temperature is lower, the average area of thenon-metal portion 80 becomes larger.

It is possible to control the proportion of the non-metal portions 80existing in the base electrode layer 50 by changing the addition of theglass component and the firing temperature. As the addition of the glasscomponent is larger and the firing temperature is higher, the proportionof the non-metal portions 80 becomes higher. Conversely, as the additionof the glass component is smaller and the firing temperature is lower,the proportion of the non-metal portions 80 becomes lower. Thecomposition of the electrically conductive paste includes about 50 vol %or more and about 80 vol % or less of the copper powder, about 5 vol %or more and about 20 vol % or less of the glass component, and othersolvents and resin components, for example.

Thereafter, the plated layer is formed on the surface of the baseelectrode layer 50 including the fired layer. In the present preferredembodiment, the first plated layer 60A is formed on the surface of thefirst base electrode layer 50A. Furthermore, the second plated layer 60Bis formed on the surface of the second base electrode layer 50B. In thepresent preferred embodiment, the Ni plated layer and the Sn platedlayer are formed as the plated layers. Upon performing the platingprocess, electrolytic plating or electroless plating may be adopted.However, the electroless plating has a disadvantage in that apretreatment with a catalyst or the like is necessary in order toimprove the plating deposition rate, and thus the process iscomplicated. Therefore, normally, electrolytic plating is preferablyadopted. The Ni plated layer and Sn the plated layer are sequentiallyformed, for example, by barrel plating.

When the electrically conductive resin layer is provided, theelectrically conductive resin layer may cover the fired layer. When theelectrically conductive resin layer is provided, an electricallyconductive resin paste including a thermosetting resin and a metalcomponent is applied on the fired layer, and then heat treatment isperformed at a temperature of about 250° C. to about 550° C. or higher,for example. Thus, the thermosetting resin is thermally cured to formthe electrically conductive resin layer. The atmosphere during the heattreatment is preferably an N2 atmosphere. Furthermore, in order toprevent scattering of the resin and to prevent oxidation of variousmetal components, the oxygen concentration is preferably about 100 ppmor less.

The multilayer ceramic capacitor 1 preferably is manufactured by themanufacturing process described above, for example.

The configuration of the multilayer ceramic capacitor 1 is not limitedto the configuration shown in FIGS. 1 to 4B. For example, the multilayerceramic capacitor 1 may include a two-portion structure, a three-portionstructure, or a four-portion structure as shown in FIGS. 7A to 7C.

The multilayer ceramic capacitor 1 shown in FIG. 7A is a multilayerceramic capacitor 1 including a two-portion structure. The multilayerceramic capacitor 1 includes, as the internal electrode layer 30, afloating internal electrode layer 35 which is not exposed at either sideof the first end surface LS1 and the second end surface LS2, in additionto the first internal electrode layer 33 and the second internalelectrode layer 34. The multilayer ceramic capacitor 1 shown in FIG. 7Bincludes a three-portion structure including, as the floating internalelectrode layer 35, a first floating internal electrode layer 35A and asecond floating internal electrode layer 35B. The multilayer ceramiccapacitor 1 shown in FIG. 7C includes a four-portion structureincluding, as the floating internal electrode layer 35, the firstfloating internal electrode layer 35A, the second floating internalelectrode layer 35B and a third floating internal electrode layer 35C.Thus, by providing the floating internal electrode layer 35 as theinternal electrode layer 30, the multilayer ceramic capacitor 1 includesa structure in which the counter electrode portion is divided into aplurality of counter electrode portions. With such a configuration, aplurality of capacitor components are provided between the counterinternal electrode layers 30, such that a configuration in which thesecapacitor components are connected in series is provided. Therefore, thevoltage applied to the respective capacitor components becomes low, andthus, it is possible to achieve a high breakdown voltage of themultilayer ceramic capacitor 1. It should be noted that the multilayerceramic capacitor 1 of the present preferred embodiment may be amultiple-portion structure of four or more portions.

The multilayer ceramic capacitor 1 may be of two-terminal type includingtwo external electrodes, or may be of multi-terminal type including alarge number of external electrodes.

In the preferred embodiments of the present invention described above,the multilayer ceramic capacitor in which the dielectric layers 20 madeof dielectric ceramic is used as a ceramic layer is exemplified as themultilayer ceramic electronic component. However, the multilayer ceramicelectronic components of the present disclosure are not limited thereto.For example, the ceramic electronic components according to preferredembodiments of the present invention are also applicable to apiezoelectric component using piezoelectric ceramic as a ceramic layer,and various multilayer ceramic electronic components such as athermistor using semiconductor ceramic as a ceramic layer. Examples ofthe piezoelectric ceramic include PZT (lead zirconate titanate) ceramicand the like. Examples of the semiconductor ceramic include spinelceramic and the like.

The multilayer ceramic capacitor 1 according to a preferred embodimentdescribed above achieves the following advantageous effects.

The multilayer ceramic capacitor 1 according to a preferred embodimentof the present invention includes the multilayer body 10 including thedielectric layers 20 functioning as the plurality of ceramic layers andthe internal electrode layers 30 functioning as the plurality ofinternal conductive layers which are alternately laminated therein inthe lamination direction T, the first main surface TS1 and the secondmain surface TS2 which are opposed to each other in the laminationdirection, the first end surface LS1 and the second end surface LS2which are opposed to each other in the length direction L perpendicularor substantially perpendicular to the lamination direction T, and thefirst lateral surface WS1 and the second lateral surface WS2 which areopposed to each other in the width direction W perpendicular orsubstantially perpendicular to the lamination direction T and the lengthdirection L, and the pair of external electrodes 40 provided on bothends of the multilayer body 10 in the length direction L and spacedapart from each other, in which the plurality of internal conductivelayers 30 include the first internal electrode layers 31 each extendingtoward and exposed at the first end surface LS1, and the second internalelectrode layers 32 each extending toward and exposed at the second endsurface LS2, in which the pair of external electrodes 40 include thefirst external electrode 40A including the first base electrode layer50A connected to the first internal electrode layer 31, and the secondexternal electrode 40B including the second base electrode layer 50Bconnected to the second internal electrode layer 32, in which the firstbase electrode layer 50A and the second base electrode layer 50B eachinclude the metal portion 70 and the plurality of non-metal portions 80existing in the metal portion 70, and in which, in a cross sectionalview perpendicular or substantially perpendicular to the width directionW, the average area of a plurality of non-metal portions 80 in the firstpopulation of a plurality of non-metal portions 80 each having acircularity of about 0.4 or less is about 12 μm² or less.

This makes it difficult for the non-metal portions 80 of the first baseelectrode layer 50A and the second base electrode layer 50B to defineand function as a path through which moisture penetrates into the insidefrom the outside, and as a result, the moisture resistance reliabilityof the multilayer ceramic capacitor 1 is increased.

In the multilayer ceramic capacitor 1 according to a preferredembodiment, it is preferable that the first base electrode layer 50A andthe second base electrode layer 50B are each a fired layer.

With such a configuration, it is possible to form the first baseelectrode layer 50A and the second base electrode layer 50B by arelatively simple method as compared with a case of forming the firstbase electrode layer 50A and the second base electrode layer 50B by athin film forming method such as a sputtering method or an evaporationmethod. Furthermore, by forming the fired layer simultaneously with thefiring of the multilayer body 10, it is possible to simplify themanufacturing process.

In the multilayer ceramic capacitor 1 according to a preferredembodiment, it is preferable that, in a cross sectional viewperpendicular or substantially perpendicular to the width direction W, aproportion of the plurality of non-metal portions 80 in the first baseelectrode layer 50A and the second base electrode layer 50B is about17.2% or less.

This also makes it difficult for the non-metal portions 80 of the firstbase electrode layer 50A and the second base electrode layer 50B todefine and function as a path through which moisture penetrates to theinside from the outside, and as a result, the moisture resistancereliability of the multilayer ceramic capacitor 1 is increased.

The present invention is not limited to the configuration of theabove-described preferred embodiments, and can be appropriately modifiedand applied without departing from the gist of the present invention.The present invention also includes combinations of two or more of theindividual desirable configurations described in the above preferredembodiments.

EXAMPLES

Examples are described below. According to the manufacturing methodsdescribed in the preferred embodiments of the present invention,multilayer ceramic capacitors of a plurality of lots manufactured sothat the average area of non-metal portions in the first population inthe base electrode layer became different values were manufactured assamples of Examples 1 to 6 and Comparative Examples. Examples 1 to 6were directed to multilayer ceramic capacitors that satisfy thepreferred embodiments of the present invention, and Comparative Exampleswere directed to multilayer ceramic capacitors that do not satisfy thepreferred embodiments of the present invention. Samples of the same lotwere manufactured under the same manufacturing conditions, and thespecifications of the base electrode layers were the same. Seventy-twosamples were prepared for each lot (Examples 1 to 6 and ComparativeExamples). Next, the prepared samples were each subjected to a moistureresistance reliability test. Furthermore, the samples after the moistureresistance reliability test were polished, and parameters such as theaverage area of the non-metal portions in the first population weremeasured by the above-described measuring method.

Each sample was manufactured according to the following specifications.

-   -   Dimensions of multilayer ceramic capacitor: L×W×T=1.6 mm×0.8        mm×0.8 mm    -   Dielectric layer: BaTiO₃    -   Capacitance: 10 μF    -   Rated voltage: 25 V    -   Base electrode layer: electrode including an electrically        conductive metal (Cu) and a glass component (thicknesses of the        base electrode layers provided on the first end surface and the        second end surface: 36 μm, respectively)    -   Plated layer: Two layer structure of Ni plated layer (2 μm) and        Sn plated layer (4 μm)    -   Internal electrode layer: Ni

Table 1 shows the measurement results of the average area of thenon-metal portions in the first population and the proportion of thenon-metal portions existing in the base electrode layer of the samplesof Examples 1 to 6 and Comparative Examples. The measurement resultswere each an average value of 10 samples randomly extracted from amongthe 72 samples.

The moisture resistance reliability tests were performed under theconditions of 85° C./85% RH. The IR values (insulating resistance)before and after the test were each measured at a rated voltage, and theamount of change was confirmed. Specifically, the IR values after acharge time of 60 seconds at a rated voltage were each measured. Asample in which the IR value after the moisture resistance test wasreduced by a power equal to or greater than 1 with respect to the IRvalue before the moisture resistance test (i.e., a sample in which theIR value was equal to or less than 1/10) was determined as an “NGsample” in which the moisture resistance reliability was poor.Furthermore, a sample in which the IR value after the moistureresistance test was reduced in a range of a power equal to or greaterthan about 0.3 to a power less than 1 with respect to the IR value(insulating resistance) before the moisture resistance test wasdetermined as an “IR-reduced sample” in which the IR value was reduced.The results are also shown in Table 1.

TABLE 1 TEST RESULTS OF TEST RESULTS OF PROPORTION OF MOISTURERESISTANCE MOISTURE RESISTANCE AVERAGE AREA OF NON-METAL PORTIONRELIABILITY RELIABILITY NON-METAL PORTION IN BASE ELECTRODE (NUMBER OFNG (NUMBER OF IR SAMPLE IN FIRST POPULATION LAYER SAMPLES) REDUCEDSAMPLES) Example 1 12.0 17.2% 0/72 7/72 Example 2 9.0 12.4% 0/72 0/72Example 3 6.3 10.7% 0/72 0/72 Example 4 6.4 7.2% 0/72 0/72 Example 5 6.11.5% 0/72 0/72 Example 6 2.3 7.5% 0/72 0/72 Comparative 14.9 18.1% 7/7222/72  Example

As apparent in the Comparative Example from Table 1, when the averagearea of the non-metal portions existing in the first population exceeds12 μm², a sample having a moisture resistance reliability of NG occurs.On the other hand, as in Examples 1 to 6, when the average area of thenon-metal portions existing in the first population is 12 μm² or less,the results of moisture resistance reliability are good. Therefore, theaverage area of the non-metal portions existing in the first populationis preferably 12 μm² or less in order to secure moisture resistancereliability.

It should be noted that, in Example 1, no samples having moistureresistance reliability of NG were generated; however, samples having IRreduced in the moisture resistance reliability test were generated.Therefore, it can be evaluated that the average area of the non-metalportions existing in the first population is more preferably about 9 μm²or less.

For example, the average area of the non-metal portions of the firstpopulation is preferably about 2 μm² or more and about 12 μm² or less,and more preferably about 2 μm² or more and about 9 μm² or less. Thisimproves moisture resistance reliability.

The proportion of non-metal portions existing in the base electrodelayer is preferably about 17.2% or less. For example, the proportion ofnon-metal portions existing in the base electrode layer is preferablyabout 1.5% or more and about 17.2% or less.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer ceramic electronic componentcomprising: a multilayer body including a plurality of ceramic layersand a plurality of internal conductive layers which are alternatelylaminated therein in a lamination direction, a first main surface and asecond main surface which are opposed to each other in the laminationdirection, a first end surface and a second end surface which areopposed to each other in a length direction perpendicular orsubstantially perpendicular to the lamination direction, and a firstlateral surface and a second lateral surface which are opposed to eachother in a width direction perpendicular or substantially perpendicularto the lamination direction and the length direction; and a pair ofexternal electrodes on both ends of the multilayer body in the lengthdirection and spaced apart from each other; wherein the plurality ofinternal conductive layers include: first internal conductive layerseach extending toward and exposed at the first end surface; and secondinternal conductive layers each extending toward and exposed at thesecond end surface; the pair of external electrodes include: a firstexternal electrode including a first base electrode layer connected tothe first internal conductive layer; and a second external electrodeincluding a second base electrode layer connected to the second internalconductive layer; the first base electrode layer and the second baseelectrode layer each include a metal portion and a plurality ofnon-metal portions in the metal portion; in a cross sectional viewperpendicular or substantially perpendicular to the width direction, anaverage area of a plurality of non-metal portions in a first populationof a plurality of non-metal portions each having a circularity of about0.4 or less is about 12 μm² or less.
 2. The multilayer ceramicelectronic component according to claim 1, wherein the first baseelectrode layer and the second base electrode layer are each a firedlayer.
 3. The multilayer ceramic electronic component according to claim1, wherein, in the cross-sectional view perpendicular or substantiallyperpendicular to the width direction, a proportion of the plurality ofnon-metal portions in the first base electrode layer and the second baseelectrode layer is about 17.2% or less.
 4. The multilayer ceramicelectronic component according to claim 1, wherein the multilayerceramic electronic component is a capacitor.
 5. The multilayer ceramicelectronic component according to claim 1, wherein the multilayer bodyhas a rectangular or substantially rectangular parallelepiped shape. 6.The multilayer ceramic electronic component according to claim 1,wherein the multilayer body includes corner portions and ridge portionsthat are rounded.
 7. The multilayer ceramic electronic componentaccording to claim 1, wherein a dimension in the length direction of themultilayer body 10 is about 0.2 mm or more and about 6 mm or less, adimension of the multilayer body in the lamination direction is about0.05 mm or more and about 5 mm or less, and a dimension of themultilayer body in the width direction is about 0.1 mm or more and about5 mm or less.
 8. The multilayer ceramic electronic component accordingto claim 1, wherein each of the plurality of ceramic layers includesBaTiO₃, CaTiO₃, SrTiO₃, or CaZrO₃.
 9. The multilayer ceramic electroniccomponent according to claim 8, wherein each of the plurality of ceramiclayers further includes a secondary component including a Mn compound,an Fe compound, a Cr compound, a Co compound, or a Ni compound.
 10. Themultilayer ceramic electronic component according to claim 8, wherein athickness of each of the dielectric layers is about 0.2 μm or more andabout 10 μm or less.
 11. The multilayer ceramic electronic componentaccording to claim 2, wherein each of the fired layers includes a metalcomponent, and at least one of a glass component or a ceramic component.12. The multilayer ceramic electronic component according to claim 11,wherein the metal component includes at least one selected from Cu, Ni,Ag, Pd, Ag—Pd alloys, or Au; the glass component includes at least oneselected from B, Si, Ba, Mg, Al, or Li; and the ceramic componentincludes at least one selected from BaTiO₃, CaTiO₃, (Ba, Ca)TiO₃,SrTiO₃, or CaZrO₃.
 13. The multilayer ceramic electronic componentaccording to claim 1, wherein a thickness of each of the first baseelectrode layer and the second base electrode layer is about 10 μm ormore and about 200 μm or less at the center thereof.
 14. The multilayerceramic electronic component according to claim 13, wherein a thicknessof each of the first base electrode layer and the second base electrodelayer is about 3 μm or more and about 40 μm or less at a portion otherthan the center thereof.
 15. The multilayer ceramic electronic componentaccording to claim 1, wherein each of the first base electrode layer andthe second base electrode layer include an Ni plated layer and an Snplated layer.
 16. The multilayer ceramic electronic component accordingto claim 1, wherein the metal portion includes at least one metalcomponent selected from Cu, Ni, Ag, Pd, an Ag—Pd alloy, or Au.
 17. Themultilayer ceramic electronic component according to claim 1, whereinthe non-metal portions include voids or a glass component including Baor Si.
 18. The multilayer ceramic electronic component according toclaim 1, wherein the average area of the plurality of non-metal portionsin the first population of the plurality of non-metal portions is about2 μm² or more and about 9 μm² or less.
 19. The multilayer ceramicelectronic component according to claim 1, wherein, in thecross-sectional view perpendicular or substantially perpendicular to thewidth direction, a proportion of the plurality of non-metal portions inthe first base electrode layer and the second base electrode layer isabout 5% or more and about 15% or less.